Older XTR M952 vs new SLX 662

Tried to find this on other discussions, but can't find it, so here goes....

I just bought a used bike (approx 7 yrs) that came originally with an XTR M952. However, the spring is shot so it won't stay in gear. They sent me a new SLX 662 to replace it.

My question is whether the it is worth the $22 spring to fix the XTR, or to go with the newer SLX Most LBS guys I talk to say that newer derailleurs at a "lower" level are actually superior to older models at a "higher" level. So is it possible that the new SLX is actually a better derailleur than the almost-vintage M952?

Finally, as a weekend warrior, would I really notice a difference one way or the other? Thanks.

Old XTR is better made than the new stuff imho. I've got a bike built up with 952 stuff. The derailleurs have 6 years of riding on them and the shifters have 2. Even with cables that are several years old the XTR stuff shifts perfect.

In terms of build quality there's no comparison, the old 950/952 series XTR goodies are far better built, tougher, and way more durable than anything made today. The rear XTR derailleur on my bike has about 10 years of use on it, and for the first 2 years it was raced all over North America by a factory pro before I bought her entire XTR groupset and put it on my bike. It still shifts as well as brand new SLX, and the front actually shifts better.

Shimano did an amazing job with the 950/952 series, it was way ahead of its time. For instance I don't think the hinged independently moving plates on its front derailleurs has ever been used on anything else. It shifted better, and the outer plate would arc down over the big ring to help keep the chain on the ring.

The 950/952 front derailleurs are awesome. They are designed with dual-plate cages that literally lift the chains in between the chainrings. They are also among the lightest front derailleurs ever made by Shimano (if not the lightest at 112g).

All the front derailleurs after the 950-952 seemed like an exercise in cost cutting. Nobody makes them like they did any more.

my current rear derailleur is a Shimano XT from 2006 that was installed on an OLD Kona Coiler Deelux (2006). I purchased the Kona used that eventually got a crack in the chain stay, so when i purchased my new frame, that XT rear Derailleur came with me..till this day that thing shifts perfect with zero issues! you would have to pry it from my dead hands or convince me to run a 10 speed in the rear lol XTR from what i heard in the past was even better..jus sayin

Most LBS guys I talk to say that newer derailleurs at a "lower" level are actually superior to older models at a "higher" level.

LBS, LBS.....They want to sell stuff. (I bet they would keep your 952 when they give you the SLX)
What others said, XTR 952 rear derailleur is a masterpiece. Replace the spring!
BTW, you can adjust the tension of the spring by turning a little knob in one of the spring supports. No other derailleur has that nowadays....

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